Method of preshaping shoe uppers



March 21, 1967 A. A. STADEN 3,399,725

METHOD OF PRESHAPING SHOE UPPERS Filed Feb. 4, 1965 2 Sheets-Sheet 1 swam 4 FTER amma 4'4 32 SWETCH GVE THES REQWN March 21, 1967 A. A. STADEN METHOD OF PRESHAPING SHOE UPPERS 2 Sheets-Sheet 2 Filed Feb. 4, 1965 United States Patent 3,309,725 IWETHOD 0F PRESHAPING SHOE UPPERS Alfred Alexander Sta-den, Weliinghorough, England, assignor to The British Boot, Shoe and Allied Trades Research Association, Kettering, Northamptonshire, Engiand, a British association Fiied Feb. 4, 1965, Ser. No. 430,327 Ciaims priority, application Great Britain, Feb. 10, 1964, 5,41ti/64 14 Claims. (Ci. 12-146) This invention relates to the treatment of leather with a view to pre-forming the same, whereby the leather may more readily be shaped to a desired contour as, for example, in making an upper part of a shoe.

The conventional method of shaping an upper forepart depends upon the application of force to draw the upper material over a last and to fasten it by mechanical means in this stretched condition. A measure of setting to the desired shape is achieved either by the mere lapse of time or by the application of means, such as heat treatment, to hasten this result. However, the leather is not always as amenable as might be desired to this deforming treatment, and powerful forces are often required to pull the leather into shape, which may cause a deterioration in the properties of the leather as well as apparent damage.

It is an object of the present invention to provide a method and apparatus for preshaping leather, so that the leather may more readily assume the required contour. Another object of the invention is to provide a method whereby the stretching of the leather which is entailed in causing the leather to assume a desired contour, may be accomplished more satisfactorily than by pulling the leather edgewise into contact with a last. Yet another object is to provide means whereby leather pieces may be lasted without having to suffer the application of unduly high tension.

The invention consists, broadly, in a method of preshaping a piece of leather in which the leather, supported in a generally flat condition at spaced positions at or adjacent its periphery, is subjected to localized stretching by lateral displacement between said positions. Generally, this displacement will be accomplished by relative movement between the supports for the leather and a plurality of mould parts. These mould parts may be arranged for separate movement, but may more conveniently be arranged for movement in unison, and may represent portions of an undulating mould surface.

In forcing a leather piece to assume a desired contour, such as the forepart of a shoe upper, the leather is conventionally held at its periphery and pulled against a mould surface (last), the mould or last surface protruding as a whole and displacing the main body of the leather laterally of the plane, corresponding generally to the last sole plate, where the leather is gripped at its periphery. However, it is found that the leather is not stretched uniformly, and in some places may even be subjected to slight compression. The stretching of the leather is to a large extent localised and occurs in separate regions situated between predetermined parts of the leather periphery. It is found that the leather may be stretched in the desired manner and thus preshaped, much more efficiently, that is to say, more uniformly and/or with a lesser pull, if the leather is held at those positions where it is to be stretched least or not at all, and the stretching displacement then brought about by a mould which bears little resemblance to the contour which is ultimately required. However, if this preshaped leather part is now lasted or otherwise moulded in substitution fora leather part which has not been given this treatment, far readier conformity with the last or other mould is achieved.

In this connection it will be understood that the expres- "ice sion preshaped does not mean that the leather necessarily assumes and retains some predetermined shape, but that the leather is stretched selectively in certain regions, corresponding to those regions where the maximum stretch is required in the ultimate shaping of the leather, so that the leather is no longer flat but exhibits predetermined regions of distention, through retention of part at least of the stretch to which it has been subjected.

In what is perhaps the most important application of the invention, an upper forepart is preshaped. The toe, the inside waist and the outside waist portions of a footwear upper forepart form three corners of a triangle. Analysis of the distortions undergone by the leather in the course of normal lasting indicates that the material between the corners of this triangle should be stretched, Whilst the centre part of the triangle should if anything be slightly compressed. In this case, therefore, the generally triangular leather piece will be gripped at its apices and held in a generally fiat condition, and then displaced by a mould having three mould parts in the form of lobes which together suggest a clover leaf, the surface contours being such that the lobes will cause the material between the gripped positions to stretch when the mould is forced between them, whilst leaving the material at the centre of the triangle relatively undisturbed.

Optionally, provision may be made for retractive movement of the jaws or other gripping devices for holding the leather at its periphery, for imparting additional stretch.

Whilst a mould for preshaping shoe upper foreparts will generally have three lobed mould parts as just described, it may have only two (for stretching the regions between the toe and waist), or it may have four if provision is made for forming a bulge at the toe.

It will in general be desirable to incorporate some provision for increasing the retention of the localized distension of the leather. This will generally entail the application of heat, and to this end, provision may be made for heating the mould parts. Alternatively, the mould parts may be used as an electrode of a dielectric heating device, or provision may be made for passing steam or hot air through the mould parts, which in this case will remain permeable. In addition, or instead, an application of moisture may be made. Thus, the upper may be preformed in a mulled condition and dried, to some extent, on the mould.

Where the mould is heated, the temperature employed may well exceed C. for normal full chrome leathers. The leather may in this case be wetted on the flesh or innerside with Water (with or without wetting agent) before fitting to the mould, or alternatively, a membrane of a suitable substance such as paper, gauze or fabric may be pre-wetted with water with or Without wetting agent and interposed between the upper material and the heated mould. In yet another alternative, the leather is stretched over the heated mould, and the leather surface not in contact with the mould is wetted. These do not of course represent all the variants which will be apparent to those skilled in the art; for example, the leather when stretched over the mould (whether heated or not) may be heated on its exposed face, or a heated, complementary mould member may be pressed down over the exposed leather face.

Normally, the mould parts will make contact with the flesh side of the leather, although similar results may be obtained if contact is made with the grain side.

By stretching a shoe vamp in flat form between three jaws holding the leather at its apices, whilst the leather is deformed by pressure applied from a mould designed to stretch the material along the sides of the triangle, and especially by using this same apparatus to set the deformation so produced, a preformed forepart may be obtained l3 which is enormously improved as regards its lasting properties.

Whilst the method of the invention has special significance in relation to leather, other materials such as plastic uppers may be pre-stretched in like a manner.

The location and extent of strains which need to be applied to a shoe upper to cause it to conform to the surface of a last can be determined by flattening shells of the last made from suitable material such as tape or plastics material. Such shells which will be familiar to those acquainted with the art, are made by covering the whole or part of the last surface with a suitable material which is afterwards removed to provide a representation of the surface contours of the last. In order to achieve the flattening of the shell, the material must of course be shrunk in various regions, and this can be accomplished for example by pleating it. The extent of the required shrinkage can then be measured, and in this way a pattern can be prepared showing the starting contour and the location and degree of stretch required so to pre-shape the initially fiat upper material that it will conform to the last with a minimum of strain. To achieve this, however, it is necessary to strain the upper in a manner which is not achieved by existing lasting machinery, but which is readily achieved by the method and apparatus of this invention.

The invention will be described further with reference to the accompanying drawings, of which:

FIGURE 1 is a plan view of a leather vamp showing the magnitude and direction of required stretch;

FIGURE 2 is a view similar to FIGURE 1 but of a different pattern;

FIGURE 3 is a view of a simple machine for pre-forming uppers by means of an undulating mould;

FIGURE 4 is a view of the upper part of the machine with a pre-heated mould fitted in position, and

FIGURE 5 is a view similar to FIGURE 4 but showing the machine in operation.

The vamp shown in FIGURE 1 comprises a tongue 1, tab points 2, a toe portion 3 and marginal side portions generally indicated by the reference numeral 4. The feather line, that is to say the line along which the lasting margin is folded under the last, is indicated by the dotted line 5. A forepart pattern such as that shown in FIG- URE 1 can in considerable measure be generated by forming a skin or shell of flexible material on the last over the required area, removing the skin or shell and flattening it. In order to accomplish this flattening, it will be found that extensive pleating or wrinkling of the flexible material is necessary. This corresponds in effect to a compression of the material, and the direction and extent of the more important lines of compression are indicated by reference numerals 6 and 7 in FIGURE 1. correspondingly, to generate the original shell, a leather pattern cut to the shape shown in FIGURE 1 requires to be stretched in the corresponding direction and to the corresponding extent. Similarly in FIGURE 2, where the same numerals identify corresponding parts of the vamp, which in this case has no tongue, the marginal ortions 4 are stretched over the region indicated from an initial length of 4 inches to a final length of 4 /2 inches, whilst the region of the tab points is given a stretch of the order of of an inch, in a direction at right angles to the centre line of the vamp. These two directions of stretch are not, of course, by any means precisely at right angles to one another but they are generally transverse to one another. Where the vamp has a tongue, this may be stretched at right angles to its centre line to a degree increasing towards the free end of the tongue. The stretch referred to in the vicinity of the tab points may be localised as shown, or more generally distributed along a line transverse to the vamp centre line.

In stretching a vamp such as shown in FIGURE 1 or FIGURE 2, it may be found advantageous not to stretch the lasting margin itself to the extent indicated, or at least 4, to arrange that the stretch is not retained to the same extent as it is above the lasting margin.

The machine of FIGURES 3-5 comprises a table-like frame incorporating a shelf 31 carrying a ram or jack 32. The jack incorporates an extensible rod 33 and a rocker 34, operation of which in an up and down direction causes the rod 33 to extend in a well known fashion. The frame 30 also incorporates a top 35 carrying three sets of jaws 36, 37 and 33. The jaws 36 and 37 are supported by blocks 39 and 40 respectively and each associated with a handle and screw mechanism 41 and 42 respectively whereby the jaws 36 and 37 may be moved. Each of the jaws point towards a generally central position above the rod 33.

A mould member 43 detach-ably rests on the top of the rod 33. This mould member is of undulating form, comprising three rounded lobes 44, 45 and 46. A handle 47 is also provided, whereby the mould member may be conveyed from an oven to the top of the jack 32. In use, a leather upper forepart 48, similar to the forepart illustrated in FIGURE 2, is gripped at its apices by the jaws 36, 37 and 38. Jaws 33 grip the toe part, whilst jaws 36 and 37 grip the waist portions. The pre-heated mould member 33 is positioned as shown in FIGURE 4, before fitting the leather forepart, and afterwards the jack rocker 34 is operated to lift the mould 43 and press it against the leather as illustrated in FIGURE 5.

To facilitate stretching the leather it may be in an already moistened or mulled condition prior to fitting in the jaws. To increase retention of the stretch imparted to the leather, the latter may if desired be additionally moistened after it has been stretched by the mould member 43. In either case, the heat of the mould member 43 dries the leather, and when it is deemed sufficiently dry it is removed from the machine.

Generally, it will be found sufiicient to position the leather manually in the jaws, the screw mechanism 41 and 42 serving to adjust the machine for different sizes of vamp. If desired, however, these mechanisms may also be used to stretch the leather additionally after the jaws have been closed.

The machine shown in FIGURES 3-5 illustrates the principles involved. In a factory machine, the actuation of the jaws and movement of the mould would be by pneumatic, hydraulic or other driven and automatically regulatable means.

I claim:

1. The method of preshaping a shoe upper forepart which comprises supporting a blank in a generally flat condition by gripping and holding the material of the blank at a plurality of spaced marginal portions only about its periphery and subsequently subjecting the thus supported blank to localized stretching between adjacent clamped portions by applying locally varying forces to selected portions of only the peripheral margins of the blank to variously stretch parts of the peripheral margins and thus preshape the blank for subsequent lasting operations.

2. The method as defined in claim 1 in which the locally variable forces are applied to the blank by engaging the blank with a molding form having a plurality of parts so shaped as to apply stretching forces of predetermined position and magnitude and causing relative movement between the gripped and held marginal portions of the blank and the parts of the form.

3. The method as defined in claim 1 in which the upper forepart is leather and which further includes the step of setting at least in part the stretch imparted to the leather by the application of heat before the leather is released from the position in which it was held.

4. The method, as defined in claim 1, in which the locally varying forces are applied to one side only of the blank.

5. The method, as defined in claim 1, in which the shoe upper forepart is of leather and the locally varying forces are applied to the flesh side of the leather.

6. The method, as defined in claim 1, in which the locally applied forces are applied in directions perpendicular to the initial substantially flat plane of the material.

7. The method of preshaping a generally triangular blank of shoe upper material which comprises applying clamps to the material of the blank only adjacent the apices of the triangle to support the blank in a generally flat extended condition, and subsequently displacing the material of the thus supported blank by forcing against it a mold having three spaced lobes shaped to stretch most the peripheral portions of the blank lying between the adjacent clamped regions to leave the material at the center of the blank relatively unstretched.

8. The method of preshaping a shoe upper forepart blank which comprises applying clamps to the material of the blank at its toe and waist portions adjacent its periphery to support the blank in a generally fiat extended condition, and subsequently subjecting the thus supported blank to localized stretching along the lateral portions of the blank by pressing a lobed mold against selected portions of one surface of the blank lying between said marginal portions with sufiicient force to displace and stretch the peripheral lateral portions of the material of the blank between the toe and Waist regions leaving the central portion of the blank relatively unstretched.

9. The method as defined in claim 8 which includes the step of causing the clamps to move in directions away from the blank to stretch the material of the blank substantially in the plane of its flat condition.

119. The method as defined in claim 8 which further includes the step of setting at least in part the stretch imparted to the leather by the application of heat before the leather is released from the position in which it was held.

11. The method, as defined in claim 8, which further includes the step of stretching the peripheral margin portion of the blank between the clamped regions of the lateral margins of the blank.

12. The method, as defined in claim 8, in which the mould has two lobes, one lobe to engage one lateral marginal portion of the blank and the other lobe to engage the other lateral marginal portion of the blank, said lobes engaging the blank between the waist portions and the toe portion, said lobes decreasing in height toward the center of the blank so as to leave the central portion of the blank relatively unstretched.

13. The method, according to claim 8, in which the mould has a lobe to engage the marginal portion of the blank between the clamps at the waist portions for stretching the waist portion, said lobe decreasing in height toward the center of the blank to leave the central portion of the blank relatively unstretched.

14. The method, as defined in claim 12, in which the mould has a lobe to engage the marginal portion of the blank between the clamps at the waist portions for stretching the waist portion, said last-named lobe decreasing in height toward the center of the blank to leave the central portion of the blank relatively unstretched.

References Cited by the Exaer UNITED STATES PATENTS 944,337 12/1909 Legg 1254.5 1,110,323 9/1914 Hamilton 1254.2 X 1,195,967 8/1916 Brock 12-542 1,313,916 8/1919 Russell et a1. 12l46 2,117,732 5/1938 Korting 1254.2 2,160,624 5/1939 Quinn et al. 12146 2,301,785 11/1942 Marx 12-54.1 2,440,845 5/1948 Cairns 1254.1 X 3,048,864 8/1962 Broadbent 1254.5

FOREIGN PATENTS 59,014 5/1913 Austria. 126,685 2/ 1932 Austria.

PATRICK D. LAWSON, Primary Examiner. 

1. THE METHOD OF PRESHAPING A SHOE UPPER FOREPART WHICH COMPRISES SUPPORTING A BLANK IN A GENERALLY FLAT CONDITION BY GRIPPING AND HOLDING THE MATERIAL OF THE BLANK AT A PLURALITY OF SPACED MARGINAL PORTIONS ONLY ABOUT ITS PERIPHERY AND SUBSEQUENTLY SUBJECTING THE THUS SUPPORTED BLANK TO LOCALIZED STRETCHING BETWEEN ADJACENT CLAMPED PORTIONS BY APPLYING LOCALLY VARYING FORCES TO SELECTED PORTIONS OF ONLY THE PERIPHERAL MARGINS OF THE BLANK TO VARIOUSLY STRETCH PARTS OF THE PERIPHERAL MARGINS AND THUS PRESHAPE THE BLANK FOR SUBSEQUENT LASTING OPERATIONS. 